This invention is directed to a stable aqueous composition of a saturated polyester polymer of relatively low acid value and a vinyl polymer prepared using a hydrocarbon wax.
It is desirable for some purposes to be able to take advantage of respective properties of polyester polymers and vinyl polymers such as acrylic polymers in a single aqueous composition, for example, an aqueous coating composition. In such compositions the compatibility of the polyester and vinyl components and the stability of these components in aqueous medium are important. It is known, for example, to incorporate hydrophilic groups such as carboxylic acid groups and/or salts thereof to aid in the solubilization or dispersion of otherwise insoluble polyester and acrylic polymers in water. However, the presence of such groups in the resultant compositions, such as coating compositions, tends to contribute to undersirable water sensitivity and water resistance of films produced from the compositions. The proximity of such hydrophilic groups to ester linkages in polyester polymers possibly may contribute to such water sensitivity. Generally, the higher the molecular weight of, for example, the polyester polymer the more hydrophilic groups per molecule which are needed for water-solubilization.
An object of the present invention is to provide a water-solubilized resin composition of a polyester polymer and vinyl polymer in which the acid value of the polyester polymer for solubilization or dispersion in water is minimized and yet the compatibility of the components with each other is enhanced so as to provide relative stability of the aqueous composition. It is also an object of the present invention to provide an aqueous composition of polyester and acrylic polymers having a low overall acid value. Other objects of the invention will become apparent to the reader infra.